diff --git a/app/assets/javascripts/discourse/lib/utilities.js.es6 b/app/assets/javascripts/discourse/lib/utilities.js.es6
index 1829e36dfe..bfb76fbbc3 100644
--- a/app/assets/javascripts/discourse/lib/utilities.js.es6
+++ b/app/assets/javascripts/discourse/lib/utilities.js.es6
@@ -441,8 +441,9 @@ export function uploadLocation(url) {
 export function getUploadMarkdown(upload) {
   if (isAnImage(upload.original_filename)) {
     const name = imageNameFromFileName(upload.original_filename);
-    return `![${name}|${upload.width}x${upload.height}](${upload.short_url ||
-      upload.url})`;
+    return `![${name}|${upload.thumbnail_width}x${
+      upload.thumbnail_height
+    }](${upload.short_url || upload.url})`;
   } else if (
     !Discourse.SiteSettings.prevent_anons_from_downloading_files &&
     /\.(mov|mp4|webm|ogv|mp3|ogg|wav|m4a)$/i.test(upload.original_filename)
diff --git a/app/jobs/onceoff/clear_width_and_height.rb b/app/jobs/onceoff/clear_width_and_height.rb
new file mode 100644
index 0000000000..226a863023
--- /dev/null
+++ b/app/jobs/onceoff/clear_width_and_height.rb
@@ -0,0 +1,15 @@
+module Jobs
+  class ClearWidthAndHeight < Jobs::Onceoff
+    def execute_onceoff(args)
+      # we have to clear all old uploads cause
+      # we could have old versions of height / width
+      # this column used to store thumbnail size instead of
+      # actual size
+      DB.exec(<<~SQL)
+        UPDATE uploads
+        SET width = null, height = null
+        WHERE width IS NOT NULL OR height IS NOT NULL
+      SQL
+    end
+  end
+end
diff --git a/app/models/optimized_image.rb b/app/models/optimized_image.rb
index a344d4f5fc..55e4080a02 100644
--- a/app/models/optimized_image.rb
+++ b/app/models/optimized_image.rb
@@ -81,6 +81,7 @@ class OptimizedImage < ActiveRecord::Base
         end
 
         if resized
+
           thumbnail = OptimizedImage.create!(
             upload_id: upload.id,
             sha1: Upload.generate_digest(temp_path),
@@ -88,6 +89,7 @@ class OptimizedImage < ActiveRecord::Base
             width: width,
             height: height,
             url: "",
+            filesize: File.size(temp_path)
           )
           # store the optimized image and update its url
           File.open(temp_path) do |file|
@@ -123,6 +125,32 @@ class OptimizedImage < ActiveRecord::Base
     !(url =~ /^(https?:)?\/\//)
   end
 
+  def calculate_filesize
+    path =
+      if local?
+        Discourse.store.path_for(self)
+      else
+        Discourse.store.download(self).path
+      end
+    File.size(path)
+  end
+
+  def filesize
+    if size = read_attribute(:filesize)
+      size
+    else
+      # we may have a bad optimized image so just skip for now
+      # and do not break here
+      size = calculate_filesize rescue nil
+
+      write_attribute(:filesize, size)
+      if !new_record?
+        update_columns(filesize: size)
+      end
+      size
+    end
+  end
+
   def self.safe_path?(path)
     # this matches instructions which call #to_s
     path = path.to_s
diff --git a/app/models/upload.rb b/app/models/upload.rb
index 276681105f..25d7ecc472 100644
--- a/app/models/upload.rb
+++ b/app/models/upload.rb
@@ -24,7 +24,7 @@ class Upload < ActiveRecord::Base
 
   validates_with ::Validators::UploadValidator
 
-  def thumbnail(width = self.width, height = self.height)
+  def thumbnail(width = self.thumbnail_width, height = self.thumbnail_height)
     optimized_images.find_by(width: width, height: height)
   end
 
@@ -41,10 +41,6 @@ class Upload < ActiveRecord::Base
     }
 
     if get_optimized_image(width, height, opts)
-      # TODO: this code is not right, we may have multiple
-      # thumbs
-      self.width = width
-      self.height = height
       save(validate: false)
     end
   end
@@ -103,6 +99,51 @@ class Upload < ActiveRecord::Base
     "upload://#{Base62.encode(sha1.hex)}.#{extension}"
   end
 
+  def local?
+    !(url =~ /^(https?:)?\/\//)
+  end
+
+  def fix_dimensions!
+    return if !FileHelper.is_image?("image.#{extension}")
+
+    path =
+      if local?
+        Discourse.store.path_for(self)
+      else
+        Discourse.store.download(self).path
+      end
+
+    self.width, self.height = size = FastImage.new(path).size
+    self.thumbnail_width, self.thumbnail_height = ImageSizer.resize(*size)
+    nil
+  end
+
+  # on demand image size calculation, this allows us to null out image sizes
+  # and still handle as needed
+  def get_dimension(key)
+    if v = read_attribute(key)
+      return v
+    end
+    fix_dimensions!
+    read_attribute(key)
+  end
+
+  def width
+    get_dimension(:width)
+  end
+
+  def height
+    get_dimension(:height)
+  end
+
+  def thumbnail_width
+    get_dimension(:thumbnail_width)
+  end
+
+  def thumbnail_height
+    get_dimension(:thumbnail_height)
+  end
+
   def self.sha1_from_short_url(url)
     if url =~ /(upload:\/\/)?([a-zA-Z0-9]+)(\..*)?/
       sha1 = Base62.decode($2).to_s(16)
diff --git a/app/serializers/upload_serializer.rb b/app/serializers/upload_serializer.rb
index a02fbef9b0..9e2098b815 100644
--- a/app/serializers/upload_serializer.rb
+++ b/app/serializers/upload_serializer.rb
@@ -5,6 +5,8 @@ class UploadSerializer < ApplicationSerializer
              :filesize,
              :width,
              :height,
+             :thumbnail_width,
+             :thumbnail_height,
              :extension,
              :short_url,
              :retain_hours
diff --git a/db/migrate/20180827053514_add_filesize_to_optimized_images.rb b/db/migrate/20180827053514_add_filesize_to_optimized_images.rb
new file mode 100644
index 0000000000..8840b57afe
--- /dev/null
+++ b/db/migrate/20180827053514_add_filesize_to_optimized_images.rb
@@ -0,0 +1,7 @@
+class AddFilesizeToOptimizedImages < ActiveRecord::Migration[5.2]
+  def change
+    add_column :optimized_images, :filesize, :integer
+    add_column :uploads, :thumbnail_width, :integer
+    add_column :uploads, :thumbnail_height, :integer
+  end
+end
diff --git a/lib/cooked_post_processor.rb b/lib/cooked_post_processor.rb
index 72423cf43a..8daef42e89 100644
--- a/lib/cooked_post_processor.rb
+++ b/lib/cooked_post_processor.rb
@@ -327,7 +327,17 @@ class CookedPostProcessor
 
     # replace the image by its thumbnail
     w, h = img["width"].to_i, img["height"].to_i
-    img["src"] = upload.thumbnail(w, h).url if upload && upload.has_thumbnail?(w, h)
+
+    if upload
+      thumbnail = upload.thumbnail(w, h)
+
+      img["src"] =
+        if thumbnail && thumbnail.filesize.to_i < upload.filesize
+          upload.thumbnail(w, h).url
+        else
+          upload.url
+        end
+    end
 
     # then, some overlay informations
     meta = create_node("div", "meta")
diff --git a/lib/upload_creator.rb b/lib/upload_creator.rb
index ea365b18b3..25d2eef45d 100644
--- a/lib/upload_creator.rb
+++ b/lib/upload_creator.rb
@@ -106,7 +106,8 @@ class UploadCreator
       @upload.extension         = image_type || File.extname(@filename)[1..10]
 
       if is_image
-        @upload.width, @upload.height = ImageSizer.resize(*@image_info.size)
+        @upload.thumbnail_width, @upload.thumbnail_height = ImageSizer.resize(*@image_info.size)
+        @upload.width, @upload.height = @image_info.size
       end
 
       @upload.for_private_message = true if @opts[:for_private_message]
diff --git a/spec/models/optimized_image_spec.rb b/spec/models/optimized_image_spec.rb
index 0b7fbd6386..9d7db74d4c 100644
--- a/spec/models/optimized_image_spec.rb
+++ b/spec/models/optimized_image_spec.rb
@@ -54,22 +54,35 @@ describe OptimizedImage do
       end
 
       it 'should work correctly' do
-        tmp_path = "/tmp/resized.png"
 
-        begin
-          OptimizedImage.resize(
-            "#{Rails.root}/spec/fixtures/images/logo.png",
-            tmp_path,
-            5,
-            5
-          )
+        file = File.open("#{Rails.root}/spec/fixtures/images/resized.png")
+        upload = UploadCreator.new(file, "test.bin").create_for(-1)
 
-          expect(File.read(tmp_path)).to eq(
-            File.read("#{Rails.root}/spec/fixtures/images/resized.png")
-          )
-        ensure
-          File.delete(tmp_path) if File.exists?(tmp_path)
-        end
+        expect(upload.filesize).to eq(199)
+
+        expect(upload.width).to eq(5)
+        expect(upload.height).to eq(5)
+
+        upload.create_thumbnail!(10, 10)
+        thumb = upload.thumbnail(10, 10)
+
+        expect(thumb.width).to eq(10)
+        expect(thumb.height).to eq(10)
+
+        # very image magic specific so fudge here
+        expect(thumb.filesize).to be > 200
+
+        # this size is based off original upload
+        # it is the size we render, by default, in the post
+        expect(upload.thumbnail_width).to eq(5)
+        expect(upload.thumbnail_height).to eq(5)
+
+        # lets ensure we can rebuild the filesize
+        thumb.update_columns(filesize: nil)
+        thumb = OptimizedImage.find(thumb.id)
+
+        # attempts to auto correct
+        expect(thumb.filesize).to be > 200
       end
 
       describe 'when an svg with a href is masked as a png' do
diff --git a/spec/models/upload_spec.rb b/spec/models/upload_spec.rb
index 1ee24f9b95..a52af4a0bd 100644
--- a/spec/models/upload_spec.rb
+++ b/spec/models/upload_spec.rb
@@ -46,6 +46,22 @@ describe Upload do
 
   end
 
+  it "can reconstruct dimensions on demand" do
+    upload = UploadCreator.new(huge_image, "image.png").create_for(user_id)
+
+    upload.update_columns(width: nil, height: nil, thumbnail_width: nil, thumbnail_height: nil)
+
+    upload = Upload.find(upload.id)
+
+    expect(upload.width).to eq(64250)
+    expect(upload.height).to eq(64250)
+
+    upload.update_columns(width: nil, height: nil, thumbnail_width: nil, thumbnail_height: nil)
+
+    expect(upload.thumbnail_width).to eq(500)
+    expect(upload.thumbnail_height).to eq(500)
+  end
+
   it "extracts file extension" do
     created_upload = UploadCreator.new(image, image_filename).create_for(user_id)
     expect(created_upload.extension).to eq("png")
diff --git a/test/javascripts/lib/utilities-test.js.es6 b/test/javascripts/lib/utilities-test.js.es6
index 82fbfe6bba..ba2448b35c 100644
--- a/test/javascripts/lib/utilities-test.js.es6
+++ b/test/javascripts/lib/utilities-test.js.es6
@@ -161,8 +161,8 @@ var testUploadMarkdown = function(filename) {
   return getUploadMarkdown({
     original_filename: filename,
     filesize: 42,
-    width: 100,
-    height: 200,
+    thumbnail_width: 100,
+    thumbnail_height: 200,
     url: "/uploads/123/abcdef.ext"
   });
 };